Trunk Flexion Anatomy and Mechanics

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Questions and Answers

What is the primary muscle involved in trunk flexion?

Transversus abdominis
Internal obliques
External obliques
Rectus abdominis (correct)

Which of the following muscles acts as accessory muscles during trunk flexion?

External obliques (correct)
Pectoralis major
Gluteus maximus
Latissimus dorsi

What is a factor that limits the range of motion in trunk flexion?

Weakness of spinal extensor muscles
Increased flexibility of abdominal muscles
Tension of the posterior longitudinal ligament (correct)
Movement of the scapulae

Where does the range of motion of trunk flexion primarily take place?

<p>Thoracic spine (D)</p> Signup and view all the answers

What is the nerve supply for the rectus abdominis muscle?

<p>Lower intercostal nerves (D)</p> Signup and view all the answers

Flashcards

Primary Trunk Flexor

Rectus abdominis is the main muscle responsible for trunk flexion.

Trunk Flexion Range of Motion

The range of movement (flexion) of the trunk, from a supine position (lying on the back) to a sitting position.

Accessory Trunk Flexors

Internal and external obliques assist in trunk flexion, working with rectus abdominis.

Factors Limiting Trunk Flexion

Ligaments like posterior longitudinal, ligamentum flavum, and interspinal/supraspinous ligaments and spinal extensor muscles, along with intervertebral fibrocartilage compression and rib contact, restrict the motion.

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Rectus Abdominis Origin

The rectus abdominis originates from the pubic crest and the ligaments surrounding the pubic symphysis.

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Study Notes

Trunk Flexion

Objectives: Students will be able to identify the primary muscles involved in trunk flexion and the range of motion for trunk flexion.

Primary Muscles

Rectus abdominis: A primary muscle for trunk flexion.

Accessory Muscles

Internal obliques
External obliques

Range of Motion & Fixation

Back lying position: Flexion of thorax on pelvis until scapulae are lifted from the table, primarily in the thoracic spine. The motion continues to sitting position due to hip flexors' reverse action with abdominal muscles acting as stabilizers.

Factors Limiting Motion

Tightness in posterior longitudinal ligaments, ligamentum flavum, interspinal and supraspinal ligaments.
Tension in spinal extensor muscles.
Compressing the intervertebral fibrocartilages.
Contact between lower ribs and abdomen.

Anatomy of Rectus Abdominis

Origin: Crest of pubis, ligaments covering front of symphysis pubis.
Insertion: Three portions into cartilages of fifth, sixth, and seventh ribs.
Nerve supply: Lower intercostal nerves.

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Description

This quiz delves into the crucial aspects of trunk flexion, focusing on the primary and accessory muscles involved. It also covers the range of motion and factors that can limit this motion, emphasizing the anatomy of the rectus abdominis. Test your understanding of these important concepts related to physical anatomy and movement.